The present invention relates to display of digital images. Some embodiments provide enhanced capabilities for testing new methods of image processing.
FIG. 1 illustrates a conventional display system 110 of the type widely used in computers, telephones, and other kinds of equipment. Display system 110 is based on an LCD (liquid crystal display) technology, and includes a display unit 114 having a subpixel array 120 with subpixels 130. A backlight unit 140 emits light passing through subpixels 130 to a viewer 150. Subpixel control circuit 160 controls the subpixels 130 to transmit more or less light from backlight unit 140 as needed to display a desired image.
The image is defined by digital image data (e.g. RGB data) 164 supplied to image processing circuit 170. Circuit 170 generates subpixel values (“SPXV”) 174 from the image data and supplies subpixel values 174 to subpixel control 160. Subpixel values 174 specify the desired state of each subpixel 130. The subpixel states indicate how transmissive the subpixels must be to display the image. Subpixel control 160 generates corresponding voltages to drive the subpixels into the desired states.
The processing performed by image processing circuit 170 depends on the type of subpixel array 120. In a color display, each subpixel 130 displays a primary color. The primary colors can be red, green and blue; or red, green, blue and white; or cyan, magenta and yellow; or some other combination of colors. Image data 164 may define the image as a number of pixels, each pixel's color being defined by color coordinates in some color space (e.g. RGB). The color space may be unrelated to the primary colors of subpixels 130. Image processing circuit 170 generates the subpixel values from the color coordinates. This operation may be complex. For example, image processing circuit 170 may sharpen the image. Also, subpixel layout in array 120 may have a complex relationship to pixel data 164. For example, an input pixel in data 164 can be mapped into an area which lacks some primary color. See e.g. PCT application published as no. WO 2006/127555 A2 on 30 Nov. 2006 incorporated herein by reference, and describing a system which maps some input pixels 164 into pairs of red and green subpixels 130, while mapping other pixels into pairs of blue and white subpixels 130. If a pixel is mapped into a pair of blue and white subpixels 130 but the pixel's color include a non-zero red coordinate, then the corresponding red luminance can be displayed by adjacent red subpixels. Generation of subpixel values 174 can be complex.
New types of image processing are periodically designed to improve image quality, reduce the cost and size of image processing circuit 170, increase the image processing speed, reduce power consumption, and possibly for other reasons. Image processing circuit 170 is typically a hardwired circuit. In order to facilitate testing of new designs, a new design may initially be implemented in software, e.g. using a development system 210 of FIG. 2. System 210 may be a computer having a computer processor 220 executing computer instructions stored in a computer storage 230. Storage 230 can also be used to store suitable data, e.g. RGB data 164 and subpixel values 174. System 210 processes the RGB data 164 and generates subpixel values 174 according to the new design. In order to test the image generated by the new design, the subpixel data 174 are provided to a conventional display system 110 of older design. The image processing circuit 170 is placed in a Bypass mode by an externally supplied bypass signal 240. In this mode, circuit 170 passes the input data to subpixel control 160, and the data get displayed by subpixel array 120.
It may be possible to provide image processing circuits with better capabilities for testing of new designs.